EP publication 0 467 071 A2 discloses a subscriber terminal in a telecommunication system. A conventional alarm tone indicating an incoming call can be replaced with vibration the user can sense. A device implementing the vibration can be located in the casing of the subscriber terminal or it can be a separate device that is connected to the subscriber terminal through a wired or a wireless data transmission connection.
Publications WO 93/15590 and U.S. Pat. No. 5,696,497 disclose a radio transceiver that employs both silent and audible alarm. Silent alarm can be implemented by vibration, for instance. The radio transceiver informs the user of an incoming call using the silent alarm and if the user does not answer the call within a predetermined time, the radio transceiver gives an audible alarm using tones. The device implementing the vibration is locate in the subscriber terminal. The radio transceiver can also automatically change the alarm mode employed from silent alarm alone to audible alarm when the radio transceiver is connected to an external power supply or a holder. The user can control the duration of the alarm and the periodic alternation of silent and audible alarms.
EP publication 0 688 125 A1 discloses a mobile station employing a vibrating alarm. A device implementing the vibration is located in a module separate from the mobile station, for instance in a battery of the mobile station. Apart from vibration, the silent alarm can be implemented with a light, an electric signal or air, for example.
Computer games employ controllers by which attempts are made to model the game's onscreen virtual reality. For instance, at the Internet address force-feedback.com there is a description of a force feedback mouse providing a tactile sensation that can be used for controlling a portable computer, for instance. By means of the mouse, it is possible to model the onscreen reality. The mouse provides tactile feedback. For instance, when the cursor clicks an onscreen button, the user feels in the mouse a snap that represents clicking. It is also possible to sense e.g. various surface materials with the mouse. If the computer display shows ice, the mouse simulates a sliding movement especially the speed of movement when the cursor is passing over the ice., as compared with the cursor moving over sand shown on screen. When moving over the sand, the mouse can also shake.
The above describes tactile alarm modes informing of an incoming call and user interfaces attempting to model virtual reality by means of touch. Mobile telephones are also known which inform the user with even vibration that he has selected a closing function, i.e. power switch-off, or an opening function, i.e. power switch-on.
In portable devices, such as mobile telephones, rather limited interest has been shown in the needs of handicapped persons. For instance, very little attention has been paid to the needs of aurally or visually impaired people. Visually impaired persons have had at their disposal programmable shortcut function keys. A person with normal eyesight has in that case programmed a telephone number to be dialed with one key. A problem with this solution is the small number of programmable keys.